This invention relates to a speech processing system and more particularly to an improvement in synthesized speech quality of a speech analysis-synthesis system which transmits speech parameters containing spectrum envelop information expressed by a plurality of line spectra in the analog form.
There has been widely employed a speech analysis-synthesis system which transmits speech parameters containing spectrum envelop information expressed by a plurality of line spectra such as well-known LSP (Line Spectrum Pairs) or by CSM (Composite Sinusoidal Model) in the analog form. In this system, pitch information is transmitted as one of the parameter data such as a pitch period for band compression.
In accordance with this conventional analysis-synthesis system employing the parameter data transmission, a speech exciting waveform is not transmitted and hence reproduction of pitch excitation time of the exciting waveform cannot be obtained. Accordingly, there is an inevitable limit to the quality of synthesized speech.